Initialise ReceiveCommand status to NOT_ATTEMPTED for all constructors

Initialise ReceiveCommand status to NOT_ATTEMPTED for all constructors

Formerly the 4-arg constructor did not do this, which was unfortunate
as that constructor's the only way for an external user of JGit to set
the /type/ of the ref-update - which you might want to do to indicate
that the update is expected to be a UPDATE_NONFASTFORWARD, and thus does
not require expensive isMergedInto() calculations:

http://dev.eclipse.org/mhonarc/lists/jgit-dev/msg02258.html

Change-Id: I84c5e4927131e105bed93e31a62da6367c78de32
Signed-off-by: Roberto Tyley <roberto.tyley@gmail.com>